Mixer circuit arrangement

Abstract

A mixer circuit employing a distributed constant circuit using a strip line includes a strip line for applying a high frequency signal and a local oscillation signal to a diode. The strip line is provided with a filter for exclusively blocking the local oscillation signal and a filter for exclusively blocking the high frequency signal. The strip line further includes a line which acts as a shortcircuit for an intermediate frequency signal and as an open impedance for the high frequency signal and the local oscillation signal.

What is claimed is: 
     
       1. A mixer circuit arrangement of a high frequency plane circuit employing a microwave strip line as a basic component wherein a diode is connected in parallel with said line and a high frequency signal and a local oscillation signal being applied at opposite ends of said line toward said diode, comprising: a first filter including a double-open-ended line of a length equal to one half of the wavelength of said local oscillation signal with a portion thereof having a length equal to one quarter of said wavelength from one end of said line being arranged adjacent to said transmission line, said first filter being coupled to the high frequency signal input line at such a point that the impedance thereof as viewed from the junction point of said diode assumes an open impedance at the resonant frequency of said first filter;   a second filter including a double-open-ended line of a length equal to one half of the wavelength of said high frequency signal and constructed in the same manner as said first filter, said second filter being coupled to the local oscillation signal input line at such a point that the impedance thereof as viewed from said junction point of said diode assumes an open impedance to the resonant frequency of said second filter;   a line conected to said junction point of said diode on the opposite side to said diode and exhibiting a substantially shorted impedance to the frequency of an intermediate frequency signal which is a frequency component equal to the frequency difference between said high frequency signal and said local oscillation signal; and   a third filter including a double-open-ended line of a length equal to one half of the wavelength of an image signal having a frequency equal to the difference between twice the frequency of said local oscillation signal and the frequency of said high frequency signal and having the same construction as said first filter, said third filter being coupled to said line connected to said junction point, at such point that the impedance thereof as viewed from said junction point of said diode assumes a shorted impedance to the frequency of said image signal; and   a line connected to the other end of said diode to take out said intermediate signal produced at said diode.   
     
     
       2. A mixer circuit arrangement of a high frequency plane circuit employing a microwave strip line as a basic component wherein a diode is connected in parallel with said line with a high frequency signal and a local oscillation signal being applied to opposite ends of said line toward said diode, comprising: a first filter including a double-open-ended line of a length equal to one half of the wavelength of said local oscillation signal with a portion thereof having a length equal to one quarter of said wavelength from one end of said line being arranged adjacent to said transmission line, said first filter being coupled to the high frequency signal input line at such a point that the impedance thereof as viewed from the junction point of said diode assumes an open impedance at the resonant frequency of said first filter;   a second filter including a double-open-ended line of a length equal to one half of the wavelength of said high frequency signal and constructed in the same manner as said first filter, said second filter being coupled to the local oscillation signal input line at such a point that the impedance thereof as viewed from said junction point of said diode assumes an open impedance to the resonant frequency of said second filter;   a line connected to said high frequency signal input line or said local oscillation signal input line and exhibiting a shorted impedance to the frequency of an intermediate frequency signal having a frequency equal to the difference between the frequency of said high frequency signal and the frequency of said local oscillation signal; and   an output line connected to the other end of said diode for taking out said intermediate frequency signal.   
     
     
       3. A mixer circuit arrangement employing a distributed constant circuit using a microwave strip line comprising: a line connecting a high frequency signal input terminal and a local oscillation signal input terminal;   a frequency converting diode having one end thereof connected to an intermediate point of said line;   a low pass filter of a distributed constant circuit configuration having the other end of said diode connected thereto and passing an intermediate frequency signal therethrough;   first band stop means coupled to said line on the side of said high frequency signal input terminal for selectively blocking only a local oscillation signal;   second band stop means coupled to said line on the side of said local oscillation signal input terminal for selectively blocking only a high frequency signal; and   third means arranged adjacent to the point on said line to which said one end of said diode is connected and exhibiting an open impedance to said high frequency signal and said local oscillation signal while grounding said intermediate frequency signal,   wherein said third means includes a line connected to said intermediate point on the opposite side thereof to said diode and exhibiting a substantially shorted impedance to said intermediate frequency signal, and a second filter in the form of double-open-ended line of a length equal to one-half of the wavelength of an image signal having a frequency equal to the difference between twice the frequency of said local oscillation signal and the frequency of said high frequency signal, said second filter being coupled to said line connected to said intermediate point at such a point that the impedance thereof as viewed from said intermediate point assumes a short circuited impedance to the frequency of said image signal.